Pressure loaded gear pump



March l0, 1959 Filed May 29. 1953 L. L. AsPELlN ETAL 2,876,705 PRESSURELOADEDv GEAR PUMP 3 Sheets-Sheet 1 March 10, 1959 ASPELIN ETAL I2,876,705

n PRESSURE LOADED GEAR PUMP Filed May 29, 1953 5 Slle's-Sheei'l 2 jdllc.2

l a5 w i ha `John E' Murray b L5M MMMHHEE March 10, 1959 L ASPUN ETAL2,876,705

` PRESSURE LOADED GEAR PUMP Filed May 29, 1953 SSheets-Sheet 3 Fl-f WA4vwd E, 590 L, f;

W w I fo/2g F' Murray bw v 'HZLHE' United States Patent O PRESSURELOADED GEAR PUMP leslie L. Aspeln, Cleveland Heights, and John F.Murray, Macedonia, Ohio, assignors to Thompson Products, Inc., acorporation of Ollio Application May 29, 1953, Serial No. 358,453

35 Claims. (Cl. 10S-126) Thisv invention relates generally to gear pumpsand, more particularly, to a gear pump having pressure loaded movableend plate means.

It has been determined that developed pressures around the periphery ofa rotary fluid displacement means of a gear pump vary as a function ofthe rotational speed of the pump and as a function of the dischargepressure.

2,876,705 Patented Mar. 10, 1959 vide movable end plate means for a gearApump variably loaded as a function of pump speed and discharge prestoengage the side face of an adjoining rotatable gear im- Accordingly,with a pressure loaded gear pump of the type using pressure loadedmovable end plate means, the total force tending to separate the matinggear and end plate and the line of action of that force tends to changewith the speed of rotation of the gear impellers. To provide a loadingforce acting on the movable end plate which will be equal and oppositeto a varying load, it would be necessary to change not only thequantitative .value of the loading force, but it would also benecesplates into sealing engagement with the side faces of the gearimpellers. Each of the respective cylinders is referenced to acorrespondingly circumferentially spaced location in the pumping chamberso that the respective areas which are utilized for pressure loading themovable end plate will be referenced to pressures generated by the pumpvarying as a function of the pump speed and discharge pressure, therebyto balance unequal pressure forces developed in the pumping cavity ofthe pump. Thus, in its broadest aspect, the present inventioncontemplates the application of non-uniform fluid pressures to selecteduniform areas of a movable end plate. It is further contemplated toprovide a plurality of circumferentially spaced non-uniform areas which,in accordance with the lprinciples of the present invention, function asreactive pressure surfaces subject to a uniform pressure. In accordancewith either provision, the unequal pressure forces developed in thepumping cavity will be balanced by the reactive pressure forces loadingthe movable end plate means into sealing engagement with the side facesofthe gears.

It is further contemplated in accordance with the principles of thepresent invention to provide a two-piece bushing-end plate means wherebya bearing sleeve member having a journal surface adapted to journal theshaft extension of a rotary gear cooperates with a movable end platemember forming a relatively axially movable radial extension of thebearing sleeve member. The provision of such a construction permits theuse of an end plate member affording an unusually large motive surface.The two part construction further affords ilexibility insofar as axialand radial alignment of the gears and the bushing-end plate part areconcerned.

It is an object of the present invention, therefore, to provide meansfor loading an end plate of a gear pump wherein the loading force willvary as a function of the pump speed and discharge pressure.

peller member.

Another object of the present invention is to provide means forbalancing unequal pressure forces developed in the pumping cavity of agear pump.

A further object of the present invention is to provide movable endplate means for a gear pump having a motive surface of suihciently largearea to accommodate the application of loading force suicient toovercome the separating force between the gear side'face and the endplate sealing face.

Many other advantages, features, and additional objects of the presentinventionwill become manifest to those versed in the art upon makingreference to the den tailed description which follows and theaccompanying sheets of drawings in which a preferred structuralembodiment of a pressure loadedv gear pump incorporating the principlesof the present invention is shown by way of illustrative example.

On the drawings:

Figure 1 is a cross sectional view of a pumping unit including acentrifugal pump in series with a gear pump incorporating the principlesof the present invention.

' Figure 2 is a plan elevational view with parts broken away and shownin cross section and withparts removedl for the sake of clarityillustrating additional details of construction of the pumping unitshown in Figure l.

Figure 3 is a cross-sectional view, somewhat reduced, takensubstantially on line III-III of Figure 1.

Figure 4 is a cross sectional view, somewhat reduced, takensubstantially on line IV-IV of Figure l.

Figure 5 is a fragmentary cross sectional view generally similar to theview of Figure 4 but showing an alternative modification provided inaccordance with the principles of the present invention.

Figure 6 is a cross sectional View taken substantially on line VI--VI ofFigure 1.

Figure 7 is a fragmentary cross sectional view somewhat similar toFigure 1 but showing an alternative embodiment provided in accordance`with the principles of the present invention.

Figures 8, 9, 10 and 1l` are diagrammatic 'views depicting one of a pairof rotatable intermeshing gears and showing how perpiheral pressuresvary with speed in a pressure loaded gear pump having movable pressureloaded end plate means. i

As shown on the drawings:

As shown in Figure 1,*the principles of the present invention areadvantageously incorporated in a pumping unit indicated generally by thereference numeral 10 comprising a sectionalizedA casing 11, the spacedsections being held in firm assembly with one another by a plurality offasteners indicated generally at 12 (Figure 2).

The pumping unit 10 is provided with an inlet 13 through which a fluidpumping medium is delivered to a centrifugal impeller 14 rotatable in avolute pumping chamber 15. The outlet of the volute pumping chamber 15forms the inlet 16 of a pumping chamber 17 provided in the sectionalizedcasing 11 and housing rotatable fluid displacement means comprising adriver gear 18 and a Yet another object of the present invention is toprodriven gear 19- The Pumping Chamber 17 S further Pf@-y 3 vided withan outlet 20. Thus, it will be appreciated that the centrifugal pump isintegral and in series with the gear pump.

Making particular reference to Figures l and 2, it will be noted -thatthe sectionalized casing 11 comprises a housing member 21 having aradially extending face indicated at 22 and in which is formed a pair ofintersecting bores which, together, form the pumping chamber 17.

The housing member 21 is further characterized by the provision of acounterbore 23 which provides adjacent the pumping chamber 17 a radiallyextending shoulder indicated at 24. y

The sectionalized casing 11 is further provided with a cover member 26having a pair of spaced bores 27, 27 for receiving the shaft extensions18a and 19a of the driver and driven gears 18 and 19, respectively.

Additionally, the cover member 26 is provided with a pair ofcounterbores 28, 28 in assembly therewith, a bearing sleeve member 29,the detailed construction of which will be described presently. j

The cover member 26 is further provided with an additional counterboreindicated at 30 of complementary size and shape to the counterbore 23provided in the housing member 21.

The cover member 26 is also provided with a radially extending face 31complementary in size and shape to the radial face 22 on the housingmember 21 and particularly characterized by the provision of a pluralityof radially spaced apart grooves 32, each receiving seal rings 33 forestablishing sealed areas between the abutting radial faces 22 and `31.

The housing member 21 is provided with a pair of spaced apart bores 33adjacent the pumping chamber 17 and each bore 33 receives a bearingsleeve` 3-4 providing a bearing journal surface for a shaft extension18h and 19b of the driver gear 18 and the driven gear 19, respectively.y w

A stationary end plate 36 is received inone end of each of theoverlapping bores providing the pumping chamber `17 and abuts againstthe respective ends of the bearing .sleeves 34, 34 along one radiallydisposed face, the other oppositely disposed radial face providing aradially extending sealing face for sealingly engaging the mating` sideface of the driver gear 18 and the driven gear 19.

In order to prevent galling, binding and seizure between the relativelyrotatable components, a conventional annularY maching relief indicatedat 37 is provided in the driver and driven gears 18 and 19,respectively.

The sectionalized casing 11 includes a housing memb'er 38 which providesa gear box 39 for receiving the shaft extensions 18b and 19b of thedriver and driven gears 18 andv19. It will be noted that the shaftextension 18b hasa gear 39 keyed thereto as at 40, which gear 39 isrotatable with the driver gear 18 and inter'rneshingly enga-ges indriving relationship witha gear 41. y

The `shaft extension 19h has a stub extension indicated at 42 receivedin a recess 43 formed in the gear member 41. A bearing sleeve 44 isinterposed between the shaft stub 42 and the walls of the recess 43thereby to provide journal support for the gear member 41.

Further journal support for the gear member 41 is provided by a bearingretainer 46 mounted in the housing member 38 and engaging the peripheralsurface of an axial extension provided on the gear member 41. The gearmember 41 is further provided with a hub 47 to which a centrifugalimpeller 48 is keyed as at `49 for rotation in the volute chamber 15.The hub 47 is threaded a's at 50 for receiving additional fasteningmeans indicated at'Sl serving to retain the centrifugal impeller 4S incorotatable assembly with the gear member 41.

The shaft extension 18a on the driver gear 18 extends througha shaftseal assembly indicated generally at 52 and received in a recess 53provided in the cover member V26. "Theshaft extension 18a is internallysplined to provide a mating coupling with a stub shaft 54, one end ofwhich is splined as at 56 for mating engagement with the shaft extension18a and the other end of which is splined as at 57 to effect couplingengagement with a suitable power source (not shown). A cover plate S8engages the end of the cover member 26 as is shown in Figure l.

Upon applying rotational force to the stub shaft 54, the driver gear 18will be rotated whereupon the centrifugal impeller 4S will also berotated through the gear train 41, 39. Fluid will thus be pumped throughthe inlet 13 through the pumping chamber 15, the centrifugal outlet andgear pump inlet 16, the pumping chamber 17 and thence through the outlet28.

The present invention particularly contemplates the provision ofimproved movable end plate means for elecitvely sealing the gears 18 and19 in the pumping chamber 17. In effecting this end, there has beenheretofore provided combination bearing bushings and end plates formedas integral members. In accordance with the principles of the presentinvention, a two-piece bushing-end plate means is provided including thebearing sleeve 29 and an end plate member indicated at 60.

As noted hereinabove, each of the bearing sleeve members 29 is receivedin a corresponding counterbore 28 in the cover member 26. Each bearingsleeve member 29 provides an internal bore forming a bearing journalsurface 61 journalling the shaft extensions 18a and 19a of the drivergear 18 and the driven gear 19, respectively.

Each bearing sleeve member 29 further includes a peripheral surfaceindicated at 62 which is spaced radially outwardly of the bearingjournal surface 61 and which is adapted to seat against the walls of thecounterbores 28 provided in the cover member 26.

The end plate member 60 provided for each respective gear'l and 19comprises an annular ring member sized and shaped to be slidablyreceived in the counterbores 23 and 30 of the housing member 21 and thecover member 26, respectively.

As shown in Figure 3, each of the end plate members 60 has a at chordalsurface so that adjacent end plate members 60 abut one another to form ajoint indicated at 63, thereby preventing rotation of the end platemembers relative to the casing 11.

Each end plate member 60 is provided with a reduced diameter portionforming, in effect, a reduced tubular extension of an outer diameterequal to the outer diameter of the corresponding driver gear 18 anddriven gear 19. Thus, there is provided a front sealing face 64 on eachend plate member 60 which extends radially and which is equal indiameter to the gears and to the intersecting bores forming the pumpingchamber 17, thereby to provide a continuous generally annular sealingface for engaging the corresponding side faces of the gears 18 and 19, l

The inner diameter of the sealing face 64 is .preferably less than theroot diameter of the gear teeth on the driver gear 1S and the drivengear 19 so that the radial sealing face 64 extends radially inwardly ofthe gear teeth diameter.

By virtue of the construction of the end plate member 60, there isprovided an axially extending peripheral face indicated at 66 whichslidingly engages the walls indicated at 67 defining the confines of thepumping chamber 17. It will be understood that the surface 66 and thewalls 67 are slidably interrelated and sealing means are providedtherebetween which can conveniently take the form of an O ring sealindicated at 68. In the embodiment shown in the drawings, the 0 ringseal member 68 is received in a groove formed in the walls 67.

The end plate member 60 also provides a radially ex tending wallindicated at 69 which confronts and is spaced from the radiallyextending wall 24 on the housing member 21 thereby to form a chamber 70.As is shown Vin Figure 6, the radially extending wall 24 is particularlycharacterizedvfby a circumferentially extending groove 71, which groovecommunicates with the inlet 16, thereby serving to minimize any dashpotv action which would impede movement of the end plate members towardthe gears 18 and 19.

As will be appreciated by those versed in the art, the end plate members60 form a relatively axially movable radial extension of the bearingsleeve members 29. Each bearing sleevemember 29 and a corresponding endplate member 60 together provide confronting circumferential peripheraland bore surfaces, respectively, which are indicated by the commonreference character 72 and which are spaced radially outwardly of thejournal bushing surface 61 so as to slidingly relate the end platemember 60 to the corresponding bearing sleeve member 29 for relativeaxial reciprocation toward and away from the corresponding gear member.

Each end plate member 60 also provides a radially extending back face74, the outer diameter of which is equal to the diameter of thecounterbores 23 and 30 formed in the housing member 21 and thecovermember 26, respectively, and the inner diameter of which beingequal to the outer diameter of each bearing sleeve member 29.`Accordingly, because the sealing face 64 is provided on the reducedtubular extension of the end plate member 60, it will be appreciatedthat the back face 74 -will always be at least coextensive in area withthe sealing face 64. As shown in the drawings, the back face 74 will beconsiderably larger in area than the sealing face 64, which provision isparticularly advantageous for the purposes of the present invention.

In accordance with the principles of the present invention, a pluralityof circumferentially spaced reactive areas are provided to load the backface 74 and means are provided to reference each respective reactivepressure area to fluid pressures generated by the pump in the pumpingcavity 17 varying as a function of pump speed and discharge pressure forbalancing unequal pressure forces in the pumping cavity.

Before describing in detail the pressure loading means, advantageousreference may be made to the diagrammatic views shown in Figures 8, 9,10 and 11. If developed pressures are checked at various points aroundthe periphery of a pumping gear in a pressure loaded gear pump, it willbe found that such pressures vary as a function of the speed of rotationand the discharge pressure. The views of Figures 8-11 exemplify suchvariance. The numbers around the periphery of each gear express inpounds per square inch the developed fluid pressure around the peripheryof a pumping gear in a gear pump rated at 600 pounds per square inch.

In Figure 8, the rotary uid displacement means are rotated atapproximately 500 revolutions per minute and it will be noted thatpressure distribution indicates a rapid increase adjacent the inlet sideof the pump.

Comparable pressure values are indicated on Figure 9 for a rotationalspeed of 1500 R. P. M. It will be noted that the line of action of theforces tending to separate a floating bearing from the mating gear hasshifted since the high pressure values have generally shifted towardsthe outlet side.

In Figure 10, for a 2500 R. P. M. speed, the shift is even morepronounced and, in Figure 1l, at 3500 R. P. M., it will be noted thatdecided changes both as to quantitative pressure value and line ofaction of pressure force have occurred.

The loading means provided in accordance with the principles of thepresent invention compensate for the variations in separating force dueto pump speed and discharge pressure.

. In the form of the invention shown in Figure 1 and the views basedthereon, the cover member 26 is provided with a plurality ofcircumferentially spaced recesses each indicated at 80. Means areprovided to confine fluid presso as to apply a reactive pressure forceagainst the back face 74 of the end plate member 60. In the form ofFigure 1, each of the recesses comprises acylinder receiving a piston81, one face of each piston 81 indicated at 82 being exposed to fluidpressure conned in the recess 80 and the opposite faceof each piston 81indicated 83 abuttingly engaging the back face 74 of the end platemember 60.

Fluid pressures generated by the pump are referenced to the respectiverecesses 80 and in this connection, a separate fluid passage 83 isprovided for each respective recess 80 referenced to the pumping chamber17 at circumferentially spaced points around the periphery of thepumping chamber 17. In other words, the -back face 74 of each end platemember 60 is acted upon by a plurality of cylinder and piston meanswhich are circum-v ferentially spaced between the inlet and outlet sidesof the pump. Each passage 83 extends from each respective recess 80 to acorrespondingly spaced point in the pumping chamber 17 directly adjacentaxially the corresponding portion of the sealing face 64 acted upon bythe pressure forces in the pumping chamber 17. By proper proportioningof the pistons 81, for any segment of the end plate member 60 there willbe a'force of equal magnitude working on both sides of the plate,namely, the sealing face 64 and the back face 74. Moreover, the fluidpressures working in the cylinders or recesses 80 will change in4proportion to the pressure distribution around the periphery of thepumping gears as the rotational speed of the pump changes.

A continuous biasing means conveniently taking the form of a coil spring84 is provided in each recess 80, one end of each spring 84 beingbottomed against the cover member 26 and the opposite end being bottomedagainst a corresponding piston 81, thereby to provide initial loading ofthe end plate member 60 against the corresponding gear. With perfecthydraulic balance of the end plate member 60, the springs 84 provide theonly positive force holding the end plate members 60 against theircorresponding gears.

It will be noted that each respective piston Slis provided with anannular groove 86 receiving an O-ring 87 so that fluid pressure in thecylinders or recesses 80 will be positively sealed.

In the form of the invention illustrated in Figure 1, the passages 83are provided by a rst passage section which is inclined radiallyoutwardly in the cover member 26 between each respective recess 80 andthe radial face 31. A second passage section is formed in each housingmember Z1 and consists of an outwardly inclined passage extendingbetween the pumping chamber and the radial face 22 on the housing member21. In order to afford a manufacturing tolerance, the intersection ofthe passage sections at the abutting radial faces 22 and 31 arecharacterized by enlarged recesses isolated between' radial inner andouter sealing members 31 in the radially spaced grooves 32.

An axially extending passage 87 is provided through each end platemember 60 between the chamber 70 and the radial face 83 on eachrespective piston 81 to insure full engagement between each respectivepiston 81 and the back face 74 of the end plate member 60.

The sectional view of the form of the invention shown in Figure 1 andillustrated in Figure 4 illustrates how each recess 80 and thecorresponding piston 81 establishes a plurality of circumferentiallyspaced reactive pressure areas of uniform size. Although the reactivepressure areas are of uniform size, it will be appreciated that adifferent fluid pressure will exist in each cylinder or recess 80 sothat the pressure forces tending to load the end plate member 60 willvary proportionately from the inlet to the outlet sides of the pump.Moreover, the pressure in each cylinder will not only differ from thatin adjoining cylinders, but in any one cylinder or recess 80,

s??? .Seleated by the Pump in each @111e recesses 80 v75 the hydraulicpressure will vary with the changesin,

pressure around the periphery of the gear and such variations Will occuras a function of the pump speed and the pump discharge pressure.

In theembodiment of Figure 5, the structural arrangement is generallysimilar to that shown in Figures l-4, however, each of the cylinders isinidcated at 80 and each yof the pistons is indicated at 81', therespective cylinders and pistons being of non-uniform size andincreasing in effective area proportionately from the inlet side of thepump toward the outlet side of the pump. Instead of referencing therespective cylinders 80 to varying pressure, a passage 88 communicatesdischarge pressure to a feeder passage 89, thereby referencing a uniformquantitative value of pressure to each respective cylinder 80', namely,the pressure in the feeder passage 89, by means of a separate passage90. There is thus provided a plurality of circumferentially spacedreactive areas of `non-uniform size, each increasing in effective areafrom the pump inlet to the pump'outlet so that the respective areas canbe referenced to pressures generated by the pump for balancing unequalpressure forces in the pumping chamber.

In the form of the invention shown in Figure 7, the end plate member isindicated at 91 and comprises a generally ring shaped member having areduced section providing a radial front face 92 sealing against theside face of a gear member 93 and a radially extending back face 94characterized by a plurality of circumferentially spaced cylinders 96,each receiving a piston 97. An axially extending pass-age 98 is providedbetween each cylinder 96 and the front'face 92, the passage 98intersecting the front face 92 radially outwardly of the root diameterof the gear teeth so as to communicate ythe 'respective cylinders 96 topressures generated by the pump at circumferentially spaced pointsaround the periphery of the pumping chamber 99 varying as a function ofthe speed of the gear 93 and the discharge pressure of the pump. Sincethe piston 97 engagingly abuts against the casing 100 and since the endplate member 91 is slidably movable in the casing member 100 and thecasing member 101, the iiuid pressure confined in the cylinder 96 by thepiston 97 will act on the reactive pressure surface formed at the bottomof the cylinder 96 to impart an axial thrust to the end plate member 91loading the end plate member into sealing engagement with the side faceof the gear 93.

A coil spring 102 is bottomed at one end against the piston 97 and isbottomed at the other end against the end plate member 91 to initiallyload the end plate member into sealing engagement with the gear 93.

In the form of the invention illustrated in Figure 7, the separatebearing sleeve member 29 may be eliminated if desired and the end platemember 91 may be provided with a bore providing a journal bearingsurface 103 for journalling the shaft extension 93a of the gear 93.

As described in connection with the form` of the invention shown inFigure l, the back face 93 of the end plate member 91 is of considerablylarger area than the front face 92 and the end plate member 91 is alsoprovided with a radially extending shoulder 104 which confronts and isspaced from a complementary shoulder 105 provided by the casing member101 thereby to form a chamber 106 referenced to a zone of lower pressuresuch as inlet pressure by a groove 107 to minimize dash pot action.

Although various minor structural modifications might be suggested bythose versed in the art, it should be understood that we wish to embody`within the scope of the patent warranted hereon all such modificationsas reasonably and properly come within the scope of our contribution tothe art.

We claimas our invention:

l. In a pump, a casing providingintersecting bores forminga pumping.chamber and having aninlet and an outlet `atopposite'sides thereof,intermeshing gears rotatable in said pumping chamber, a movable endplate for each bore having a rst end face to sealingly engage the sideface of a corresponding gear and a second end face providing a motivesurface of larger area than said first end face, said first end facebeing subjectfto non-uniform fluid pressure forces in said pumpingchamber varying in quantitative amount from the inlet to kthe outletsides of the pump, circumferentially spaced loading means exertingloading forces on said second end face to balance the unequal pressureforces in said chamber acting on said first end face, said loading meanscomprising pressure reactive areas of non-uniform size and receivingfluid pressure generated by the pump applied over the respective areasto balance the unequal pressure forces in the pumping chamber.

2. In a pump, a casing providing intersecting bores forming a pumpingchamber and having an inlet and an outlet at opposite sides thereof,intermeshing gears rotatable in said pumping chamber, a movable endplate for each bore having a first end face to sealingly engage the sideface of a corresponding gear and a second end face providing a motivesurface of larger area than said first end face, said first end facebeing subject to non-uniform uid pressureforces in said pumping chambervarying in quantitative amount from the inlet to the outlet sides of thepump, and circumferentially spaced loading means exerting loading forceson said second end face to balance the unequal pressure forces in saidchamber acting on said first end face, said loading means comprisingpressurel reactive areas of uniform size and of means communicatingfluid pressure generated by the pump varying in quantitative amount fromthe respective areas nearest the inlet'side of the pump to therespective areas nearest the outlet side of the pump, thereby to balancethe non-uniform pressure forces in the pumping chamber.

3. In a pump, a casing providing intersecting bores forming a pumpingchamber and having an inlet and an outlet at opposite sides thereof,intermeshing gears rotatable in said pumping chamber, a movable endplate for each bore having a first end face to sealingly engage the sideface of a corresponding gear and a second end face providing a motivesurface of larger area than said first end face, said first end facebeing subject to non-uniform fluid pressure forces in said pumpingchamber varying in quantitative amount from the inlet to the outletsides of the pump, and circumferentially spaced loading means exertingloading forces on said second end face to balance the unequal pressureforces'in said chamber acting on said rst end face, said loading meanscomprising fluid pressure reactive members engaging said motive surface,and means communicating pressure generated by the pump thereto, each ofsaid fluid pressure reactive members having an `effective reactive areavarying from an adjacent pressure reactive member and increasing fromthe inlet side of the pump to the outlet side ofthe pump for balancingunequal pressure forces in the pumping chamber.

4. In a pump, a casing providing intersecting bores forming a pumpingchamber and having an inlet and an outlet at opposite sides thereof,intermeshing gearsrotatable in said pumping chamber, a movable end platefor each bore having a first end face to sealingly engage the side faceof a corresponding gear and a second end face providing ay motivesurface of larger area than said first end face, said first end facebeing subject to non-uniform uid pressure forces in said pumping chambervarying in quantitative amount from the inlet to the outlet sides of thepump, and circumferentially spaced loading means exerting loading forceson said second end face to balance the unequal pressure forces in saidchamber acting on said first end face, said loading means comprisingfluid pressure reactive members engaging said motive surface andproviding spaced uniform areas between the inlet and the outlet of 'thepump, and means communicating pressures generated by the pump *whichvary in Vquantitative amount in correspondingly spacedl areas in thepumping chamber between the inlet and the outlet of the pump to therespective uniform areas to balance the non-uniform pressures in thepumping chamber.

5. In a pump, a casing providing intersecting bores forming a pumpingchamber having an inlet and an outlet at opposite sides thereof,intermeshing gears rotatable in said pumping chamber, said casing havingradially extending walls adjacent said bores, a movable end plate memberfor each bore, each end plate member having an end face received in acorresponding one of said bores to sealingly engage the side of acorresponding gear, an annular radially outwardly extending face on saidend plate member overlying said casing walls, and a second end face onsaid end plate providing a motive surface coextensive with both of saidfaces, said iirst mentioned end face being subject to non-uniform uidpressure forces in said pumping chamber varying from the inlet to theoutlet sides of the pump, and loading means exerting a non-uniformloading force on said second end face varying from the inlet to theoutlet sides of the pump, thereby to move said end plate into sealingengagement with the gears.

6. In a pump, a casing providing intersecting bores forming a pumpingchamber having an inlet and an outlet, rotatable intermeshing gears insaid pumping chamber for moving fluid from said inlet to said outlet,said casing having a radially extending wall adjacent said bores, amovable end plate member for each bore, each end plate member having anend face received in a corresponding one of said bores to sealinglyengage the side of a corresponding gear, a second end face on said endplate member providing a motive surface greater in area than said iirstend face, and means communicating and confining fluid pressuresgenerated by the pump which vary in quantitative amount in spaced areasin the pumping chamber between the inlet and the outlet of the pump tocorrespondingly spaced and selected areas of said motive surface tobalance the non-uniform unit pressures acting on said first end face insaid pumping chamber. 7. In a pump, a casing providing a pumping cavityhavlng an inlet and an outlet and an end plate member movable toward andaway from the cavity comprising a substantially tubular portion having aradial pressure sealing face of the same outer dimension as and receivedin said cavity and adapted to sealingly engage rotary fluidydisplacement means in the cavity, and a radially extending flange atthe opposite end of said end plate member of larger dimension than saidcavity and providing a sub-- stantially annular face overlying saidcasing and a radial, face spaced therefrom providing a motive pressureloading surface of larger sized area than said sealing face.

y 8. In a pump, a casing having an inlet and an outlet,. a bore in saidcasing providing a pumping cavity and a. counterbore in said casingadjacent said pumping cavity,y intermeshing rotatable gears in saidpumping cavity for moving fluid from the inlet to the outlet andproviding: radial side faces spanning said bore, shaft extensions onsaid gears projecting from said radial side faces andA extending fromone side of said gears through said counterbore, a movable bushing insaid counterbore andA around said shaft extensions for journalling saidshaft extensions on said one side of said gears in said casing saidbushing having a reduced Atubular portion received. in said bore, saidreduced tubular portion having an. annular end face providing a sealingface for engaging: acorrespondng gear radial side face, said bushinghaving means forming a motive pressure face on its oppositeend of largerarea than said sealing face to load said bushing into sealing engagementwith said gears.

9. In a pump, a casing having a bore providing a pumping cavity, amovable bushinghaving a small end of generally tubular configurationreceived in said bore,. said small end having a radial sealing facespanning said, pumping cavity, a radially outwardly extending flange atthe opposite end of said bushing providing a radial end Wallfattheendof-said bushing and on one sidev of said;-

flange, and a radially extending generally annular wall on the otherside of said liange, said casing havinga counterbore for receiving saidflange, said casing having a radial wall between said bore and saidcounterbore confronting said annular wall on said bushing and spacedtherefrom to provide a pressure space isolated from opposite ends ofsaid bushing, and pressure fluid means communicating with said pressurespace.

l0. In a pump, a movable bushing having a generally tubularconfiguration and providing a radially outwardly extending liange at oneend providing a radial wall at one end of said bushing and on one sideof said flange, and a radially extending generally annular wall on theother side of said flange, said bushing having a radial sealing face atthe other end of said bushing, a casing having a bore providing apumping cavity spanned by said radial sealing face, said casing having acounterbore receiving said flange, said casing having a radial wallbetween said bore and said counterbore confronting said annular wall andsaid bushing and spaced therefrom to provide a pressure space isolatedfrom opposite ends of said bushing, means providing a passageway to thepump inlet from said pressure space to minimize dash pot action andloading means exerting a force varying from the inlet to the outletsides of the pump and acting on said radial end wall to move saidbushing toward said pumping cavity.

1l. In a pump, a movable bushing having a generally tubularconfiguration and providing a radially outwardly extending iiange at oneend providing a radial end wall .at one end of said bushing and on oneside of said flange, and a radially extending generally annular wall onthe other side of said ange, said bushing having a radial sealing faceat the other end of said bushing, a :casing having a bore providing apumping cavity spanned lby said radial sealing face, said casing havinga counterbore receiving said flange, said casing having a radial Iwallbetween said bore and said counterbore confronting said annular wall onsaid bushing and spaced therefrom to provide a pressure space isolatedfrom opposite ends of said bushing, and means communicating pressuresgenerated by said pump to said radial end wall to move said bushingtoward said pumping cavity.

l2. In a pump, a movable bushing having a generally tubularconfiguration and providing a radially outwardly extending flange at oneend providing a radial end wall at one end of said bushing and on oneside of said liange, and a radially extending generally annular wall onthe other side of said flange, said bushing having a radial sealing faceat the other end of said bushing, a casing having a bore providing apumping cavity spanned -by said radial sealing face, said casing havinga counterbore receiving said flange, said casing having a radial wallbetween said bore and said counterbore confronting said annular wall onsaid bushing and spaced therefrom to provide a pressure space isolatedfrom opposite ends of said bushing, means providing a passageway to thepump inlet from said pressure space to minimize dash pot action, andmeans communicating pressures generated by said pump to said radial endwall to move said bushing toward said pumping cavity.

13. In a pump, a movable bushing having a generally tubularconfiguration and providing a radially outwardly extending iiange at oneend providing a radial end wall' at one end of said bushing and on oneside of said flange, and a radially extending generally annular wall onthe other side of said ange, said bushing having a vradial sealing faceat the other end of said bushing, a casing having a bore providing apumping cavity spanned by said radial sealing face, said casing having acounterbore receiving said liange, said casing having a radial wallbetween said bore and said counterbore confronting said annular wall onsaid bushing and spaced therefrom to provide a pressure space isolatedfrom oppositerends of saidbushing, a plurality, of 'circumferentiallyspaced pressure reactive means acting'on said radial end wall -to movesaid bushing toward said pumping cavity and a corresponding plurality ofpassages in said casing between said pressure reactive means and aplurality of corresponding circumferentially spaced areas in saidpumping cavity to communicate respective pressures generated by saidpump at said spaced areas to each respective reactive means for loadingsaid bushing toward said pumping cavity and for balancing unequalpressure forces in said pumping cavity.

14. In a pump, a movable bushing having a generally tubular congurationand providing a radially outwardly extending flange at one end providinga radial end wall at one end of said bushing and on one side of saidange, and a radially extending generally annular wall on the other sideof said flange, said bushing having a radial sealing face at the otherend of said bushing, a casing having a bore providing a pumping cavityspanned by said radial sealing face, said casing having a counterborereceiving said flange, said casing having a radial wall between saidbore and said counterbore confronting said annularvwall on said bushingand spaced therefrom to provide a pressure space isolated from oppositeends of said bushing, a plurality of circumferentially spaced pressurereactive means acting on said radial end wall to move said bushingtoward said pumping cavity and a corresponding plurality of passages insaid casing between said pressure reactive means and a plurality of'corresponding eircumferentially spaced areas in said pumping cavity tocommunicate respective pressures generated by said pump at said spacedareas to each respective reactive means for loading said bushing towardsaid pumping cavity and for balancing unequal pressure Aforces in saidpumping cavity, and means providing a passageway to the pump inlet fromsaid pressure space to minimize dash pot action.

15. A pump comprising a pair of meshing rotatable gears, a housinghaving two intersecting bores providing a pumping cavity for said gearsand further including an inlet and an outlet, said gears having axiallyspaced radial side faces on opposite sides thereof, fixed end platemeans in said housing sealingly engaging the side faces on one side ofsaid gears, floating end plate means in said housing sealingly engagingthe side faces on the other side of gears, said oating end plate meanshaving a motive surface, means including said floating end plate meansforming a plurality of circumferentially spaced cylinders each having apiston movable therein and engaging said motive surface to move saidfloating end plate means relative to said housing into sealingengagement with said gears, and means providing separate passages forsaid cylinders referenced to said pumping cavity at circumferentiallyspaced points on the periphery of the Acorresponding gear axiallyadjacent the floating end plate, whereby the loading pressures aredifferent for each piston.

16. A pump comprising a pair of meshing rotatable gears, a housinghaving two intersecting bores providing a pumping cavity for said gearsand further including an inlet and an outlet, said gears having axiallyspaced radial side faces on opposite sides thereof, fixed end platemeans in said housing sealingly engaging the side faces on one side ofsaid gears, iloating end plate means in said housing sealingly engagingthe side faces on the other side of said gears, said floating end platemeans having a motive surface, means including said iioating end platemeans forming a plurality of circumferentially spaced cylinders eachhaving a piston movable therein and engaging said motive surface to movesaid floating end plate means relative to said housing into sealingengagement with said gears, and means providing separate passages forsaid cylinders referenced to said pumping cavity at circumferentiallyspaced points on the periphery of the corresponding gear axiallyadjacent the floating end plates, 'whereby the loading pressures aredifferent foreach piston, anda continuous biasing meansactingon `saidllloating end plate means to maintain an unbalance on the floating endplate means in the direction of the pumping cavity.

17. In a pump, a pair of meshing rotatable gears having radial sidefaces, pressure loaded movable end plate means comprising an end platemember providing a sealing face equal in diameter to the outsidediameter of the gears, and a radial extension on said end plate memberproviding a radially extending motive surface spaced axially from thegear and having a larger area than the area of the sealing face, andmeans including said end plate member forming a-plurality ofcircumferentially spaced cylinders and pistons working on said motivesurface to move said sealing face into sealing engagement with acorresponding gear side face, and means communicating different fluidpressure to said cylinders to work on said pistons compris- Ving passagemeans referencing each respective cylinder to pressures generated by thepump at axially adjacent circumferentially spaced points around theperiphery of the gears.

18. In a gear pump, a pair of meshing rotatable gears each having shaftextensions, pressure loaded movable end plate means comprising agenerally annular end plate member for each gear spaced radiallyoutwardly of the shaft extension and providing a sealing face equal indiameter to the outside diameter of the gear and extending radiallyinwardly of the root diameter of the teeth on the gear, and a bearingseparate from said end plate member having an outer peripheral surfaceslidably supporting said end plate member and an inner bore surface insaid bearing providing a journal Ebearing surface for the shaftextension, a radial extension on said end plate member providing amotive surface having a larger area than the area of said sealing faceand duid pressure motor means working on said motive surface to movesaid end plateinto sealing engagement with the gear. j 19. In a gearpump, a pair of meshing rotatable gears each having shaft extensions,pressure loaded movable end plate means comprising a generally annularend plate member for each gear spaced radially outwardly of the shaftextension and providing a sealing face equal in diameter to the outsidediameter of the gear and extending radially inwardly of the rootdiameter of the teeth on the gear, and a bearing separate from said endplate member having an outer peripheral surface slidably supporting saidend plate member and an inner bore surface in said bearing' providing ajournal Ibearing surface for the shaft extension, a radial extension onsaid end plate member providing a motive surface having a larger areathan the area of -said sealing' face and fluid pressure motor meansworkingv on said motive surface to move said end plate into sealingengagement with the gear, said fluid pressure motor means comprising aplurality of circumferentially spaced cylinder and piston Ymeanscommunicating pres-v sures generated by the pump at correspondinglycircumferentially spaced and axially adjacent points around theperiphery of the gear to circumferentially spaced points on said endplate member.

20. In a gear pump, a pair of meshing rotatable gears each having shaftextensions, pressure loaded movable end plate means comprising agenerally annular end plate member for each gear spaced radiallyoutwardly of the shaft extension and providing a sealing face equal indiameter to the outside diameter of the gear and extending radiallyinwardly of the root diameter of the teeth on the gear, and arbearingseparate from said end plate member.

sures generated by the pump at correspondingly circumferentiall'y spacedand axially adjacent points around the,

periphery of the gear to circumferentially spaced points on said endplate member, and a spring to load each piston with a continuous biasingforce, thereby to maintain an unbalance on said end plate member in thedirection of said gears.

y2'1. In a pump, a pair of meshing rotatable Igears having boreproviding a pumping cavity for the gears and a counterbore receiving theend plate member, there being a radial-wall between said bore and saidcounterbore spaced? from said radial extension on said end plate memberand forming together therewith an annular pressure space, and meanscommunicating said pressure space to an area at low pressure to minimizedash pot action, and a plurality of circumferentially spaced cylindersand pistons workingon said motive -surface to move said sealing faceinto sealing engagement with a corresponding gear side face, and meanscommunicating iiuid pressure to said cylinders to work on said pistons.e

-22. In aj pump, a pair of meshing rotatable gears having radial' sidefaces, pressure loaded movable endxplate means comprising an end platemember providing a sealing face equal in diameter to the outsidediameter of one of the gears, and a radial extension on said end platemember providing a motive surface on the side of said endp'late memberoppositely disposed from the gear and having a larger area than the areaof said sealing face, means providingA a plurality of circumferentiallyspaced recesses'at` said motive surface, means confining uid pressure insaid recesses to apply pressure thrusts to said end plate member atcircumferentially spaced points for movingsaid sealing face into sealingengagement with a corresponding gear side face.

23. In a pump, a pair of meshing rotatable gears having radial sidefaces, pressure loaded movable end plate means comprising an end platemember providing a sealing face equal in diameter to the outsidediameter of one of the gears, and a radial extension on said end platemember providing a motive surface ou the side of said end plate memberoppositely disposed from the gear and having a larger area than the areaof said sealing face, said end plate member having a plurality ofcircumferentially spaced recesses opening in said motive surface, a plugmember in each recess confining fluid pressure therein, a spring in eachrecess acting on said end plate member, and a passageway extendingaxially from each recess through said end plate member and intersectingsaid sealing face outside the root diameter of the gears to referenceeach respective recess to pressures generated by the pump atcircumferentially spaced points around the periphery of the gears whichpressures vary as a function of pump speed and pump discharge pressure.

24. In a pump, a pair of meshing rotatable gears having radial sidefaces, pressure loaded movable end plate means comprising an end platemember providing a sealing face equal in diameter to the outsidediameter of one ot the gears, and a radial extension on said end platemember providing a motive surface on the side of said end plate memberoppositely disposed from the gear and having a larger area than the areaof said sealing face, casing means providing a plurality ofcircumferentially spaced recesses at said motive surface and providing apumping chamber for said gears, a plug member in each recess confiningfluid pressure therein, a spring in each recess acting against said endplate member, and a passageway extending axially from each recessthrough said end plate member to said pumping chamber at circumf-14ferentially spaced points around the periphery of the gears to referenceeach respective recess to pressures generated by the pump, such pressurevarying as a function of pump speed and pump discharge.

25. In a pump, a housing having an inlet and an out-` let and providinga pumping cavity, a backing plate for said cavity in said housing havinga pressure force receiving back surface forming together with saidhousing, a plurality of circumferentially spaced reactive pressure areasof uniform size and means providing a passageway from each respectivereactive pressure area axially through said backing plate to saidpumpingV cavityreferencing said areas to pressures generated by the pumpat circumferentially spaced points around the periphery of the pumpingcavity, such pressures varying as a function of pump speed and dischargepressure for balancing unequal pressure forces in the pumping cavity.

26. In a pump, a housing having an inlet and an outlet and providing apumping cavity, a backing plate for said cavity in said housing having apressure force receiving back surface forming, together with saidhousing, a plurality of circumferentially spaced reactive pressure areasof uniform size, and means formed to operatively extend axially betweensaid areas and said pumping cavity and referencing each respective areato pressures generated by the pump at circumferentially spaced portionsin the pumping cavity, such pressures varying as a function of pumpspeed and discharge pressure forebalancing unequalpressure forces in thepumping cavity.

27. In a pump, a housing having an inlet and an outlet and providing apumping cavity, a backing plate for said cavity in said housing having apressure force receiving back surface forming together with saidhousing, a plurality of circumferentially spaced reactive pressure areasof uniform size and means referencing each respective kpressure area tocircumferentially spaced portions of said pumping cavity each containingHuid pressure Varying in quantitative amount from the inlet to theoutlet sides of the cavity to balance unequall pressure forces in thecavity,

28. A fluid pump having a suction side, a discharge` side, a rotatablepumping member, an axially movable, pressure loadable end plate having amotive surface, means including said motive surface forming a pluralityof uniformly sized circumferentially spaced pressure reactive areasdisposed in a circumferential row extending from the suction to thedischarge sides of the pump, and means referencing the respective areasto correspondingly circumferentially spaced portions of said pumpingmember each at different pressures generated by the pump atcircumferentially spaced points around the periphery of the pumpingmember and such pressures varying as a function of pump speed anddischarge pressure for balancing unequal pressure forces on the endplate.

29. In a pump, a housing having an inlet and an outlet and providing apumping cavity, a shiftable plate closing one end of said cavity in saidhousing and being subject to pressures in the cavity which increasetoward the outlet side of the cavity, said shiftable plate having aradial extension providing a back face of a larger area than the side ofsaid plate in said cavity, and means forming together with said backface a plurality of uniformly sized circumferentially spaced pressurereactive areas each having means referencing same to pressures generatedby the pump at correspondingly circumferentially spaced points aroundthe periphery of the pumping cavity and varying as a function of pumpspeed and discharge pressure to produce balancing forces urging theplate toward the cavity in proportion to the unequal forces urging theplate away from the cavity.

30. In a pump, a casing providing intersection bores forming a pumpingchamber having an inlet and an outlet at opposite sides thereof,intermeshing gears rotatable in said pumping chamber, said casing havingradially extending walls adjacent said bores, a movable motive surfacecoextensive with both of said faces, said.

end-face being subject to non-uniform lluid pressure forces in saidpumping chamber varying from the inlet to the outlet sides of the pump,and loading means exerting a non-uniform loading force on said secondend face varying. from the inlet to the outlet sides of the pump to movesaidend plate into sealing engagement with the gears.

3l. In a pump as defined in claim 30, said loading means comprisingpressure-reactive areas of non-uniform size and receiving iluid pressuregenerated by the pump applied over the respective areas to balance theunequal pressure forces in the pumping chamber.

32. In a pump as dened in claim 30, said loading means comprisingpressure-reactive areas of uniform size and of means communicating fluidpressure generated by the pump varying in quantitative amount from therespective areas nearest the inletl side of the pump to the respectiveareas nearest the outlet side of the pump," thereby to balance thenon-uniform pressure forces in'V the pumping chamber.

33. In a pump, a movable bushing having a generally tubularconiiguration and providing a radially outwardly extending 'ange at oneend providing a radial wall at one end of said bushing and on one sideof said ange, and a radially extending generally annularwalll on theother side of said ange, said bushing having a` radial sealing face atthe other end of saidfbushingQa casing'having a bore providing a pumpingcavity spanned by said radialsealing face, said casingl having acounter-jv bore receiving said `ange, said casing havinga radial wallbetween said bore and said counterbore confronting said annular wall andsaid bushing and spaced therefromfm tovprovide a pressure spacerisolated from opposite ends of rsaid bushing, means providing apassageway ,tothe pumpinlet from said pressure space tofminimizedashpotaction and loading means exerting a .force varying. fromy theinlet to the outlet sides of the-pump andacting on said radial end wallto move said bushingtowards said pumping cavity, and against the unequal4pressure forcesl existing in said pumping cavity.

34. In a pump as dened in claim 33, saidloading means comprisingpressure-reactive areas of nonlunifo'rm size and receiving fluidpressure generatedby the pump.- applied over the respective areas tobalance the,.un equal pressure forces in the pumping chamber'.

35. Ina pump as deiinedin claim.33, said loading means comprisingpressure-reactive areas of. uniform,r size and of means communicatingfluid pressurey generated.- by the pump varying in quantitative amountfromthe respective areas nearest the inlet side ofthe pump *toI therespective areas vnearest the outlet side of the pump, thereby tobalance the non-uniform pressure forces in'. the pumping chamber.

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